The invention relates to gas lasers in general, and more particularly to improvements in flowing gas lasers, such as axial flow CO.sub.2 lasers. Still more particularly, the invention relates to improvements in gas lasers of the type disclosed in commonly owned copending German patent application Serial No. 38 01 481 published Aug. 4, 1988.
The copending German patent application discloses a gas laser with an optical resonator and conduits connecting the gas-discharging outlet to the inlet of the resonator. The conduits cause the gas to pass through a compressor and a heat exchanger. An advantage of such laser is its compactness.
The trend in the development of gas lasers, particularly CO.sub.2 lasers, is toward higher outputs. The efficiency of presently known gas lasers is relatively low, especially the so-called plug efficiency which is intended to denote the ratio of achieved light output to current consumption.
U.S. Pat. No. 4,089,176 granted May 16, 1978 to Ashe for "Heat Storage Method and Apparatus" discloses a method of and an apparatus for operating power turbo-machinery. A graphite heat storage core is employed to heat compressed gaseous fluid for subsequent expansion across a fluid turbine in order to generate rotary mechanical power output. FIG. 1 of the patent shows a radial compressor which supplies gaseous fluid to a noncombusting heat storage element or apparatus by way of a heat exchanger and a conduit. The heat storage element or apparatus supplies compressed gaseous fluid to a turbine by way of a conduit, and the turbine is driven to transmit torque to the rotary component or components of the compressor. The rotary component or components of the turbine are connected with the rotary component or components of the compressor by a rigid shaft. The shaft extends beyond the turbine and serves to transmit torque to a driven part, such as the propeller of a torpedo. Gas which has undergone expansion in the turbine is returned to the compressor by way of the heat exchanger. The patent to Ashe does not discuss a laser.
German Pat. No. 338108 granted Jun. 14, 1921 to Kasparek discloses a combination of a blower and a turbine. The low-pressure unit of the apparatus is connected with a high-pressure impeller assembly and comprises four stages. Air which is drawn through the intake of the apparatus passes through the four stages to an outlet and thence to the first stage of the high-pressure impeller assembly. The thus compressed air is discharged or is admitted to the inlet of the turbine proper. The purpose of the patented apparatus is to drive the compressor at a maximum speed. Compressed air is used up, either entirely or in part, and the unused part is conveyed to and serves to drive the turbine wheel. This patent fails to mention a laser for obvious reasons.
A conventional flowing gas laser is disclosed in U.S. Pat. No. 4,686,680 granted Aug. 11, 1987 to Hoag et al.
U.S. Pat. No. 3,634,778 granted Jan. 11, 1972 to Melikian et al. discloses a closed-cycle gas laser system with a first turbine downstream of two heat exchangers which cool the gas issuing from the laser, and with a second turbine immediately upstream of the gas inlet of the laser. The second turbine is used for generation of electric current, and the first turbine is used to compress the gas.